When scaling a MySQL database, it's essential to consider horizontal sharding as an option before reaching vertical limits. Horizontal sharding involves distributing data across multiple nodes while maintaining the same schema, whereas vertical sharding splits tables into separate clusters. Database operations like write throughput and read throughput can be affected by the size of a single cluster, leading to increased latency and operational challenges. Sharding can help improve scalability, cost optimization, parallelization, and SLAs, making it an attractive solution for handling larger workloads, data sizes, and throughput capacities.